Abstract--The interindividual age-related decrease in baroreflex sensitivity (BRS) was reported in many cross-sectional studies. However, the long-term intraindividual decrease in BRS has never been confirmed by longitudinal studies. Data obtained from a 5-year prospective study designed to assess the 5-year stress effects on blood pressure (BP) provided the opportunity to assess longitudinal aging process on spectrally determined BRS (S-BRS) using the cross spectral analysis. This analysis was carried out in 205 men aged between 18 and 50 years who had 2 valid beat to beat BP recordings (Finapress) at a mean 5-year interval. At inclusion and at end of follow-up, S-BRS was significantly correlated with age (r=-0.50, P<0.001, r=-0.33, P<0.001 respectively). Interestingly, the slopes and the intercepts were not significantly different at a 5-year interval. This result is in favor of the good reproducibility of S-BRS. The attenuation with age of S-BRS was calculated at 3.6% a year. This decrease was slightly higher than the one obtained with the baseline data (2.3% per year). This longitudinal study provided, for the first time, an estimate of the slope of the age-related physiological S-BRS decrease in a mid-aged healthy male population. Our findings reinforce the interest of evaluating spontaneous BRS reported to predict hypertension and cardiovascular events in various populations.